/**
 * I18n.js
 * Internationalization module for Tank Adventure.
 * Auto-detects language from WeChat system info.
 * Supports {variable} placeholder interpolation.
 */

const zhLang = require('./zh');
const enLang = require('./en');

// ============================================================
// Language Detection
// ============================================================
let _currentLang = 'en'; // default fallback

try {
  const sysInfo = wx.getSystemInfoSync();
  const lang = (sysInfo.language || '').toLowerCase();
  // zh_CN, zh_TW, zh_HK, etc.
  if (lang.startsWith('zh')) {
    _currentLang = 'zh';
  }
} catch (e) {
  // Fallback to English if wx API is unavailable
  _currentLang = 'en';
}

const _langPacks = {
  zh: zhLang,
  en: enLang,
};

// ============================================================
// Translation Function
// ============================================================

/**
 * Get translated text by key.
 * Supports {variable} placeholder interpolation.
 *
 * @param {string} key - The translation key, e.g. 'menu.title'
 * @param {Object} [params] - Optional parameters for interpolation
 * @returns {string} The translated text
 *
 * @example
 * t('menu.title')           // => '坦克探险' or 'Tank Adventure'
 * t('pvp.hp', { count: 3 }) // => '生命 x3' or 'HP x3'
 */
function t(key, params) {
  // Try current language first
  let text = _langPacks[_currentLang] && _langPacks[_currentLang][key];

  // Fallback to English
  if (text === undefined && _currentLang !== 'en') {
    text = _langPacks.en[key];
  }

  // Fallback to key itself
  if (text === undefined) {
    return key;
  }

  // Interpolate {variable} placeholders
  if (params) {
    text = text.replace(/\{(\w+)\}/g, (match, name) => {
      return params[name] !== undefined ? String(params[name]) : match;
    });
  }

  return text;
}

/**
 * Get the current language code.
 * @returns {string} 'zh' or 'en'
 */
function getLang() {
  return _currentLang;
}

/**
 * Set the language manually (for testing or future settings).
 * @param {string} lang - 'zh' or 'en'
 */
function setLang(lang) {
  if (_langPacks[lang]) {
    _currentLang = lang;
  }
}

module.exports = { t, getLang, setLang };